Plasma heating by magnetoacoustic wave propagation in the vicinity of a 2.5D magnetic null-point

Abstract

Context. Magnetohydrodynamic (MHD) waves have significant potential as a plasma heating mechanism. Finding a suitable wave dissipation mechanism is a very tough task, given the many observational constraints on the models, and this has resulted in the development of an important research community in solar physics. The magnetic field structure has an important role in the solar corona heating. Here, we investigate in detail current sheet mode generation via magnetic reconnection and mode conversion releases some of the free magnetic energy and produces heating. In addition, energy conversion is discussed completely. Moreover, nonlinear effects on density variations and, in turn, mode conversion are pursued. Aims. In order to assess the role of magnetoacoustic waves in plasma heating, we have modeled in detail a fast magneto-acoustic wave pulse near a magnetic null-point in a finite plasma-β. The behavior of the propagation and dissipation of the fast magneto-acoustic wave is investigated in the inhomogeneous magnetically structured solar corona. Particular attention is given to the dissipation of waves and coronal heating and energy transfer in the solar corona, focusing on the energy transfer resulting from the interaction of fast magneto-acoustic waves with 2.5D magnetic null-points. Methods. The shock−capturing Godunov−type PLUTO code was used to solve the ideal MHD set of equations in the context of wave-plasma energy transfer. Results. It is shown that magneto-acoustic waves could be a viable candidate to contribute significantly to the heating of the solar corona and maintain the solar corona at a temperature of a few million degrees. The temperature is not constant in the corona. Coronal heating occurs near magnetic null points. It is found that magnetic reconnection, phase mixing and mode conversion contribute to the heating. Moreover, nonlinear fast and slow magnetoacoustic waves are decoupled except in β = 1 layer.